Gaseous electric discharge lamp device



Dec. 18, 1934. w. UYTERHOEVEN ET AL 1,984,502

GASEOUS ELECTRIC DISCHARGE LAMP DEVICE Filed April 17, 1954 INVENTORS ATTORNEY Patented Dec. 18, 1934 UNITED STATES GASEOUS ELECTRIC DISCHARGE LAMP DEVICE Willem Uyterhoeven and Cornelis Verburg, Eindhoven, Netherlands, assignors to General Electric Company, a corporation of New York In the Netherlands April 21 Application April 17, 1934, Serialilo. 721,057

2 Claims.

The present invention relates to gaseous electric discharge lamp devices.

The flickering of the light emitted by a gaseous electric discharge lamp operating on alternating current is materially reduced by providing the lamp with a thermionic cathode and three anodes andby connecting the lamp to a three phase alternating current supply source. The cathode is connected to the neutral line of the three phase current source and each of the anodes is connected to a charged line of the current source. When a metal vapor, such as the vapor of a clifiicultly v-aporizable metal, is a component of the gaseous filling of such lamps the metal vapor travels toward the cathode during the operation of the lamp. By a diflicultly vaporizable metal we mean those metals having a vapor pressure of less than one millimeter at a temperature of 200 C. Metals in this class are sodium, lithium, potassium, rubidium, mag nesium, zinc and cadmium. The travel of the metal vapor toward the cathode is particularly pronounced in the case of highly electro-positive metal vapors, such as sodium vapor. As a result of the travel of the metal vapor toward the cathode less metal vapor is present in the discharge path in the region of the anodes than in the region of the cathode during the operation of the lamp. The light emitted by the lamp is thus different in color and intensity at different parts of the lamp and the luminous efiiciency of the lamp is below the maximum. Furthermore, there is a danger of a flash-over or short-circuit between the anodes of such a vapor lamp.

The object of the present invention is to provide a gaseous electric discharge vapor lamp adapted to operate on three phase alternating current in which the above disadvantages are avoided. Another object of the invention is to provide an eflicient gaseous electric discharge vapor lamp device which is a concentrated source of non-flickering, high intensity light. Still further objects and advantages attaching to the device and to its use and operation will be apparent to those skilled in the art from the following particular description.

In accordance with these objects the invention comprises a gaseous electric discharge lamp device the container of which consists of three parallel, tubular legs of the same diameter connected to each other and located in a triangle. An electrode which is electron emitting when heated is sealed into the end of each of said legs opposite that end connected to the other of said legs and a gaseous atmosphere comprising a diflicultly vaporizable metal is present in the container. The three legs of the container are closely adjacent (the space between the walls of said legs is equal to twice the diameter of one of the legs of said container at the maximum and is preferably smaller than the diameter of one of said legs). Since there are no anodes in closely spaced positions in the container the possibility of a flash-over between the anodes is eliminated. Even though each of the three electrodes functions as such during at least twothirds of the operating period the metal vapor does not collect in the vicinity of one electrode since each electrode has alternately a positive and a negative charge with respect to one of the other of said electrodes and since the container is symmetrical in construction so that each electrode carries the same discharge current as the other electrodes. The adjacent legs of the container radiate heat to each other which facilitates the development and retention of an effective metal vapor pressure in the lamp and which decreases the heat loss thereof. The mutual heating of the legs of the container and the consequent evaporation of the metal vapor is beneficial in avoiding the travel of the metal vapor toward one of the electrodes. The above described structure of the container of the new and novel lamp device makes the lamp a concentrated source of high intensity light.

- The arrangement of the legs in a triangle is particularly advantageous when the gaseous filling emits visible resonant rays in addition to other visible rays when excited to luminescence. A

gaseous filling comprising a metal vapor, such as the vapor of one or more of the following metals, emits such raysz-sodium, lithium, potassium and rubidium. When the lamp device is operated on three-phase alternating current there is a period in which no discharge takes place in one of the parallel legs of the container which would cause flickering in the light emitted by the lamp. The resonant rays emitted by the discharge in the other two legs of the container strike the gas in that leg of the container wherein no discharge takes place. The resonant rays are absorbed by the metal vapor moleculespresent in the leg of the container which excites these molecules which emit light when they return to the basic, fundamental, or unexcit'ed state. The flickering of the light emitted by the device is thus considerably reduced.

In the drawing accompanying and forming part of this specification an embodiment of the invention is shown, in which Fig. 1 is a front elevational, schematic, partly sectional view of the new and novel lamp, and

Fig. 2 is a sectional view along the line 2-2 of Fig. 1.

Referring to the drawing the lamp comprises a container having three parallel legs 1, 2 and 3 of the same diameter and length which are connected to each other at one end thereof. A pair of electrodes 4 and 5 are sealed into the ends of each of said legs 1, 2 and 3 as shown. Said electrode 4 consists of a coiled metal filament, such as a tungsten filament having another metal filament, such as a nickel filament wrapped around it and a coating of electron emitting material applied to said filaments. Said electrode 4 is electron emitting when heated. Said electrode 5 consists of a cylindrical sheet of metal, such as a nickel sheet, and surrounds said electrode 4. Said electrode 5 is electrically connected to said electrode 4 as shown. Said electrodes 4 are heated to an electron emittingtemperature by connecting the leads thereof to a heating-current trans- -former or said electrodes 4 are brought to this temperature by the discharge, when desired.

As shown in Fig. 2 of the drawing the three legs 1, 2 and 3 of the container are located in a triangle and are parallel to each other. The distance between the walls of the legs 1, 2 and 3 is, for example, approximately 2 or 3 mm. and the diameter of said legs 1, 2 and 3 is approximately 20 mm. The container has a gaseous atmosphere therein comprising a rare gas, such as neon, and a vaporizable material, such as sodium. The light emitted by the lamp is rich in the yellow rays characteristic of sodium vapor when excited to luminescence by the passage of an electric discharge therethrough. The lamp is mounted in a double walled jacket 6 having the space between the walls thereof evacuated which reduces the heat emission of lamp to a minimum. It will be understood, of course, that in a complete lamp unit a body of heat insulating material is provided to close off the space between the container and the jacket 6 from the outside atmosphere and that a base is provided to support the Jacket 6 and the lamp mounted therein. These parts have been omitted from the drawing for purposes of simplicity of illustration.

In a gaseous electric discharge lamp device having the above structure the metal vapor does not travel toward one of the thermionic electrodes and the lamp is an efflcient source of high intensity, substantially non-flickering light when the lamp is operated on a three phase current supply source.

While we have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated andin its use and operation may be made by those skilled in the art without departing from the broad spirit and scope of the invention, for example, each of the legs 1, 2 and 3 is made in two parallel parts and the container then consists of six parallel legs, when desired.

What we claim as new and desire to secure by Letters Patent of the United States is:-

l. A gaseous electric discharge device comprising a container, thermionic electrodes sealed therein, a gaseous atmosphere therein comprising a metal vapor, said container having three parallel legs arranged in a triangle, each of said container legs having a thermionic electrode sealed therein, the distance between said legs being less than twice the diameter of said legs.

2. A lamp unit comprising in combination a heat conservator and a gaseous electric discharge device comprising a container, thermionic electrodes sealed therein, a gaseous atmosphere therein comprising a metal vapor, said container having three parallel legs arranged in a triangle, each of said container legs having a thermionic electrode sealed therein, the distance between said legs being less than twice the diameter of said legs, said lamp device being mounted in said heat conservator.

WILLEM UYTERHOEVEN. CQRNELIS VERBURG. 

